A Detailed Guide to Sichuan Pepper Cultivation Techniques and Management Methods

Planting Time: The planting period for Sichuan pepper seedlings should be determined according to the climate characteristics of each region and the growth conditions of the seedlings. Generally speaking, it can be divided into two planting seasons: spring and autumn. In high-cold regions with dry spring climate and little soil moisture, autumn planting is preferable. At this time, if the pepper seedlings are relatively mature, they can be planted in August-September; if the shoot tips of the pepper seedlings are relatively tender, planting can be postponed to September-October. When planting pepper seedlings in autumn, part of the tender shoots and tender leaves should be pruned off to reduce water evaporation and improve the survival rate. In hilly and mid-mountain areas with more rain in spring, it is better to plant early in spring when the pepper seedlings sprout. The 10 days before and 10 days after the Spring Equinox is the optimal period; if seedlings are transported from far away for planting, this must be done before the seedlings sprout. Before transport, the seedlings should be packaged and treated. If wrapped with straw, then place the seedling roots in plastic bags to keep them warm (the whole plant must not be put into the plastic bag).

Digging Holes and Planting: In order for Sichuan pepper to grow and develop well after being established, large holes should be dug and sufficient basal fertilizer applied at planting. Generally, the planting holes are 50-60 cm square, with 3-5 kg of farmyard manure and 50 g of superphosphate applied per plant; the fertilizer should be mixed evenly with the soil, and 100 g of fresh lime powder added to prevent root rot. After planting and filling with soil and watering, the holes should be covered with soil again to prevent soil moisture evaporation in the holes. In places with a lot of crushed stone, the method of covering the holes with crushed stone is more effective.

Spacing between Plants and Rows for Establishment: This is determined according to the terrain, soil fertility, Sichuan pepper variety, and the growth management technical measures to be adopted in the future. In large continuous pure Sichuan pepper forests, a plant-row spacing of 1.5 x 2.5 m is generally used. For agro-forestry intercropped Sichuan pepper orchards, a row spacing of 4 x 5 m is generally used. The principle is: where the slope is steep, the plant-row spacing is small; where the slope is gentle, the plant-row spacing is large. Where the soil is fertile and thick, the plant-row spacing is large; where the soil is barren and thin, the plant-row spacing is small. Where the plant form is large, the plant-row spacing is large; where the plant form is small, the plant-row spacing is small. If a flatland pepper orchard requires mechanized plowing, strip planting or wide-and-narrow row spacing for establishment can be used. It is necessary both to make full use of soil fertility and light energy and to adapt to the growth and development of Sichuan pepper, so as to achieve the goals of high yield, stable yield, good quality, and long life for the Sichuan pepper.

Seedling Management: For Sichuan pepper seedlings planted with leaves, if the branches and leaves wilt and curl, more leaves can be pruned as needed to maintain a balance between water supply and demand, so as to help the seedlings survive. In windy areas, support posts should be set up beside the seedlings to prevent them from being shaken by the wind, which would affect survival. If the seedlings become crooked due to irrigation, they should be straightened promptly. If there is a long drought with no rain, irrigate promptly; once the surface soil is slightly dry, loosen the surface soil promptly to reduce soil moisture evaporation. However, the number of irrigations should not be too many, so as not to destroy the soil structure and affect new growth. After planting, in order to reduce soil moisture evaporation, grass or crushed stone can also be used to cover the holes. At the same time, attention should also be paid to avoiding damage such as trampling by people and livestock.

Newly planted young trees should all undergo rotating hole expansion to facilitate the growth and development of the root system of young Sichuan pepper trees. In Sichuan pepper orchards established on barren slopes and wastelands, because the soil layer is shallow and the soil structure is poor, hole expansion work is especially important.

After deep plowing, the air and water conditions in the soil are improved, which is conducive to the decomposition and transformation of soil organic matter and mineral fertilizers, thus raising soil fertility. At the same time, deep plowing and turning the soil and increased application of organic fertilizer can promote soil maturation, improve soil structure, and benefit the growth and development of the Sichuan pepper root system.

Acidic soil should be given more alkaline fertilizer; alkaline soil should be given more acidic fertilizer. Sandy soil has poor fertilizer retention and should be fertilized frequently; clay soil has good fertilizer retention and can be fertilized somewhat heavily.

The fertilization methods for Sichuan pepper orchards include hole application, ring trench application, radial trench application, and short strip trench application. Flatland pepper orchards mostly use ring or radial trench application; mountain and slope pepper orchards are suitable for hole application or short strip trench application. Regardless of the fertilization method, the fertilization trenches or holes should be dug below the outer edge of the tree canopy. This is because in this area there are many fibrous roots of the pepper tree, which is conducive to absorption. Applying fertilizer at the root crown or outside the canopy will result in waste of fertilizer. After fertilization, soil must be covered immediately to prevent nutrient volatilization.

In addition, advantage can also be taken of the ability of branches, leaves, and fruits to absorb nutrient elements to varying degrees by carrying out root-outside fertilization (foliar fertilization) on the canopy, so as to meet the Sichuan pepper tree's need for a certain fertilizer. From after the Sichuan pepper flowers fade until 15-20 days before harvest, using potassium dihydrogen phosphate compound fertilizer for root-outside fertilization can increase yield by 8.5%.

(1) Basal fertilizer: From after picking the pepper until the spring of the following year before the Sichuan pepper sprouts, this is the period for applying basal fertilizer, but applying basal fertilizer immediately after picking the pepper is best. Basal fertilizer is mainly organic fertilizer, mixed with phosphate fertilizer. Applying basal fertilizer in autumn, when the soil is moist and the ground temperature is relatively high, is conducive to the reproduction of soil microorganisms, enabling organic matter to be effectively converted into inorganic salts and quickly absorbed by the Sichuan pepper root system, increasing tree nutrition and serving to restore tree vigor. At the same time, it also helps raise winter soil temperature and promotes the normal growth and development of Sichuan pepper the following year.

If for some reason basal fertilizer cannot be applied in autumn, then supplementary application should continue before the winter freeze. For winter fertilization, in areas with dry climate and little soil moisture, more water should be applied; if 50% biogas slurry is mixed in, it is even better.

When applying basal fertilizer, the amount depends on the size of the tree and the yield level. Generally, for a 6-7-year-old Sichuan pepper tree bearing 1-2 kg of Sichuan pepper per plant, 5-10 kg of stable manure (pen manure) can be applied, mixed with 150-250 g of superphosphate (phosphate fertilizer).

(2) Topdressing: Mainly decomposed human and livestock manure or nitrogenous inorganic fertilizer, combined with potassium fertilizer. For Sichuan pepper topdressing, within one annual growth cycle, there must be no fewer than two applications. The first topdressing is applied from late April to early May with human and livestock manure. It promotes robust growth of new shoots, increases leaf thickness, and improves photosynthetic capacity. It also plays a major role in improving fruit set and the development of young fruit. The second topdressing is applied from late June to early July with a quick-acting nitrogen fertilizer to promote flower bud formation and fruit enlargement. If this topdressing can be applied in time, it will not only promote increased yield in the current year and improve the quality of Sichuan pepper, but also lay the foundation for continued yield increases in the following year.

For the topdressing amount, for 6-7-year-old Gong pepper, the first topdressing is 5-10 kg of human and livestock manure per plant, and the second is 50-100 g of quick-acting nitrogen fertilizer. If other fertilizers are used for topdressing, the amount can be appropriately increased or decreased and adjusted flexibly.

Training and pruning is an important technical measure in Sichuan pepper production. Through training and pruning, Sichuan pepper can obtain a reasonable tree structure and make full use of space, light, and nutrient conditions, so as to achieve the goals of high yield, stable yield, and long life.

Training and pruning must adapt to and coordinate with conditions such as soil, fertilizer, sunshine, and temperature in order to play a positive role. If the role of pruning is one-sidedly emphasized while other conditions or management measures are ignored, not only will the goal of high yield not be achieved, but it will also cause adverse consequences such as delayed fruiting of young trees, low yield of large trees, and shortened lifespan.

Pruning Period

Generally speaking, pruning can be carried out throughout the entire dormant period from leaf fall to before sprouting. However, in areas with frost damage, pruning in early spring after thawing and before sprouting is best. This can avoid frost damage to the pruning cuts.<br>

In addition to winter pruning, summer pruning can also be carried out according to different local conditions. For example, some water sprouts can be pinched or shortened, and dense slender branches inside and outside the canopy can be thinned in time to facilitate ventilation and light penetration and reduce nutrient consumption.

Summer pruning has a greater weakening effect on Sichuan pepper than winter pruning; therefore, this method is mostly used during the young and vigorous tree stage. At present, Sichuan pepper production mainly uses winter pruning.

Pruning Methods

Pruning methods are generally divided into two types: thinning and heading. Thinning can promote flowering and fruiting; heading is conducive to producing strong new shoots and strengthening growth.

During the young and vigorous stage of Sichuan pepper, the method should mainly be thinning, combined with thinning and heading. During the full fruiting period, heading should be the main method, combined with heading and thinning; during the aging stage of Sichuan pepper, heading is mainly used for renewal.

(1) Thinning is cutting branches off from the base. Its effects: (1) Remove overly dense branches, crossing branches, overlapping branches, weak slender branches, and branches growing in inappropriate positions, so that the main and lateral branches are well matched and symmetrical, allowing ventilation and light penetration and saving nutrient consumption. (2) Remove dry, dead branches and diseased and pest-infested branches to reduce disease and pest damage. (3) Remove dense branches on the outer part of the canopy so that the inside of the canopy is ventilated and lit, improving the fruit-setting rate in the inner canopy. At the same time, it also plays a role in improving fruit quality.

(2) Heading is cutting off part of a branch. Its effects: (1) Suppress strong vigorous vegetative branches and water sprouts, causing them to sprout lateral branches that become fruiting branches. (2) Stimulate weaker branches to produce strong new shoots or moderate fruiting branches. (3) Heading fruiting branches reduces flower quantity, increases vegetative branches, and balances alternate bearing. (4) Heavily prune aging main and lateral branches to stimulate the growth of vigorous new shoots, renew the canopy, and rejuvenate tree vigor. (5) Pinching is also a means of heading, and it can reduce nutrient consumption early.

When training, light and ventilation conditions should first be considered. Under the premise of ventilation and light penetration, gradually cultivate a strong, evenly distributed framework to form a high-yield and stable-yield tree structure. However, because the characteristics of Sichuan pepper varieties differ, their tree forms cannot all be the same. For example, the most suitable tree forms for Gong pepper and Shu pepper are the multi-main-branch clump form and the natural open-center form; Qin pepper is mostly the natural open-center form.

(1) Multi-main-branch clump form: The characteristic of this tree form is that there are 4-5 main branches at the base, and the entire tree structure is clump-shaped. The specific training method is: after one-year-old Sichuan pepper seedlings are established, select and retain 4-5 healthy new shoots in different directions at the base of the trunk as main branches, and cut off weak slender and overlapping branches. In the first year, generally no heading is done, so the canopy expands quickly; by the second year, a small number of flower buds can form on the upper lateral branches of some main branches. Fruiting begins in the third year. Thereafter, attention should be paid each year to appropriately thinning overly dense branches. When entering the full fruiting stage, a combination of heading and renewal pruning (cutting perennial branches back to the branching point) and thinning should be used so that the tree is both ventilated and lit and the interior is prevented from becoming hollow and the fruiting position from moving outward.

The advantages of the multi-main-branch clump form are: light pruning, quick shaping, large canopy, and both early fruiting and early full fruiting; main branches grow robustly; both per-plant yield and yield per unit area are high.

(2) Natural open-center form: The tree structure of the natural open-center form is: trunk height 20-30 cm, with three main branches evenly arranged on the trunk, each main branch extending in a certain direction, selecting and retaining lateral branches on the main branches and vigorously cultivating them, letting them extend outward as much as possible so that the canopy forms two layers, and retaining many small branches on the main and lateral branches to increase fruiting sites.

The advantages of the natural open-center form are: the canopy is open, light conditions are good, which is conducive to the formation of internal and external fruiting branches; fruiting is three-dimensional, which can increase yield; the subordinate relationships are clear and the structure is firm; although the center of the canopy is hollow, water sprouts produced in the middle can be used for fruiting; it is conducive to the prevention and control of diseases and pests, to reducing longhorn beetle damage, and to the removal of weeds; the disadvantages are: the number of main branches is small; the distance is close, so there seems to be a certain limitation in the use of space.

Pruning of Mature Trees

The pruning of Sichuan pepper differs in method and degree because of differences in variety and tree age. For young and vigorous Gong pepper and Shu pepper trees, thinning should be the main method so that they quickly expand their canopy and take shape. At the same time, appropriately retain more small branches to become auxiliary branches and fruiting branches, so as to facilitate early fruiting and more fruiting. For strong branches, leave them unpruned; for weaker branches, head them to promote the growth of strong branches. Heading should be light rather than heavy; generally cutting off 1/3 or 1/4 of the branch is sufficient. For Gong pepper and Shu pepper in the full fruiting period, heading should be the main method. Through heading, fruiting branch groups are continuously renewed, and at the same time branches at all levels are continuously rejuvenated, promoting growth and the formation of fruiting branches. In addition, during this period, attention should also be paid to appropriately retaining some vegetative branches inside the canopy; even water sprouts should be noted for use through heading, so as to avoid the interior of the canopy becoming hollow and prevent the fruiting position from moving outward. The pruning degree for trees in the full fruiting period should be determined according to the tree. Generally, for robustly growing trees, pruning should be light; for weakly growing trees bearing too much fruit, pruning should be heavy. In pepper orchards with alternate bearing, in an on-year the fruiting branches should be heavily pruned and more vegetative branches retained or induced; in an off-year more fruiting branches should be retained and some vegetative branches appropriately thinned. In any pepper orchard with serious alternate bearing, if the above pruning methods are used together with other agricultural technical measures, the alternate bearing phenomenon can certainly be solved within 3-5 years.

The latent buds of Sichuan pepper trees have a relatively long lifespan, and pruning cuts also heal relatively easily. Therefore, for aging trees, while strengthening fertilizer and water management, the skeletal branches can be renewed by rotational cutting back. After the whole Sichuan pepper plant has aged, whole-plant renewal should be carried out promptly.